Motorcycle Repair: Ehaust Damage to a Motocrosser, stroke cycle engines, worst case scenario

Question
MAKE:KAWASAKI MODEL:125 YEAR:1995 2 stroke.Last Sunday at a motocross track I damaged my exhaust pipe. A rock flew up and hit it. There is a hole in the exhaust but not visible, I could hear air hissing out. There is a big dent where it hit. The dent is on the part of the exhaust-pipe that is closest to the ground, that is underneath the "U" shape. I would like to know if it can be repaired, and if so, how? If it cannot be repaired maybe you would be able to tell me what make and/or model of exhaust-pipe would best suit the bike.
ajcregan@hotmail.com.
I would very much appreciate it if you could help me with my problem. Thanking you,
          Aidan.  

Answer
Hi Aidan,

A dent and/or hole can change the performance characteristics of the pipe. Serious engine damage may result is worst case scenario. Especially with two-stroke cycle engines, pipe design is critical for proper engine performance and cylinder scavenging.

I would need to see the defects before advising on repair options. Have a local machinist or someone in the pits at the track inspect the damages.

My expertise is with roadracing, but I recommend Toomey Racing products. Search on-line for their pipes.

Respectfully,
Mark Shively